Experiment on dynamic mechanical properties of mine bolts
To study the dynamic mechanical properties of mining bolts under impact load,we employed the common bolt materials for rock burst roadways as examples from Inner Mongolia and Shaanxi mining areas.The static and dynamic mechanical properties of bolts were tested by means of AW-1500 microcomputer controlled electro-hydraulic servo testing machine and drop hammer impact testing machine,which provided the bolt load displacement curve,impact force time history curve,displacement time history curve and other data.It was found that the time history curve of bolt impact force can be divided into three stages:sharp increase stage,stable stage and attenuation stage.With the increase of impact times or impact energy,the peak impact force of the bolt increases gradually,and the impact force of the bolt varies 200～300 kN.When the bolt reaches the impact breaking point,the peak impact force is between 250～300 kN.Under the impact load,the necking of the breaking position of the anchor rod is not significant,obviously showing brittle fracture characteristics.The dynamic breaking load is slightly bigger than its static breaking load,while the elongation is greatly reduced,and that after fracture under dynamic load is about 10%.The research results can provide some experimental basis of design and material selection for rock bolts support in rock burst roadways.
deep roadwayboltimpact loadhammer impactmechanical properties
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